Shipping container for radioactive material

ABSTRACT

A body means has a cavity therewithin for receiving radioactive material and comprises side wall means including radiation shielding material as well as opposite ends which also include radiation shielding material. A combined energy absorbing and radiation shielding means is supported at opposite ends of the body means and extends outwardly thereof. The combined energy absorbing and radiation shielding means comprises a body of lead covered by a relatively thin layer of readily deformable material.

Elnited S Backus 1 SHIPPING CONTAINER FOR RADIOACTIVE MATERIAL [75] Inventor:

Assignee:

Filed:

Appl. No.:

May 24, 1971 Harold A. Backus, Wynwood, Pa.

N L Industries,1nc., New York, N.Y.

us. 01. ..250/ 0 Int. Cl. 62 5/00 Field of Search 250/108 R, 108 ws,

References Cited UNITED STATES PATENTS Smith 250/108 R Bonilla et a1 250/108 R Nov. 6, 1973 3,531,644 9/1970 Koster 250/108 R X Primary Examiner-Archie R. Borchelt Attorney-Robert L. Lehman, Fred Floersheimer and Jay D. Gordon [57] ABSTRACT 1 Claim, 1 Drawing Figure PATENTEUHUV 6 ms 3770.964

INVENTOR HAROLD A. BACKUS .1441 ID. 600M ATTORNEY SHIPPING CONTAINER FOR RADIOACTIVE MATERIAL BACKGROUND OF THE INVENTION The present invention relates to a new and novel shipping container for radioactive materials, and more particularly to a container for shipping spent fuel elements utilized in nuclear reactors and the like. The present invention may be utilized for shipping any sort of radioactive material and is particularly useful for shipping irradiated nuclear fuel elements which are normally mounted on railraod cars or trailers and the like for transport from one place to another.

A principle consideration of such shipping containers is to provide adequate radiation protection for personnel who may be in the area of the container. It is necessary to design such containers so that they will withstand considerable impact forces which may occur in the event of an accident or the like. Such shipping containers must be designed so as to withstand a 30 foot frccfall on an unyielding surface with the container impacting flat on one of its ends including the end hav ing a removable closure means or head. Such closure means have seal means associated therewith for providing a seal between the interior and exterior of the shipping container. It is essential to maintain an effective seal between the closure means and the body means of the container even when the end of the container having the closure means thereat receives severe impact loads. It is accordingly necessary to prevent deformation of the rigid clamping area adjacent the seal.

Conventional shipping containers for radioactive material employ massive additional steel structures around both the upper and lower ends of the shipping container to absorb energy, thereby attenuating shock loads transmitted to the container and its contents. This arrangement is expensive in construction and substantially adds to the overall weight of the shipping container which, of course, is a very undesirable feature.

SUMMARY OF THE INVENTION The body means of the shipping container according to the present invention has a cavity therewithin for receiving radioactive material and it comprises side wall means including radiation shielding material as well as opposite ends including radiation shielding means. At least one of said ends includes a removable closure.

A combined energy absorbing and radiation shielding means is supported at each of the opposite ends of the container and extends outwardly thereof. This combined energy absorbingand radiation shielding means includes deformable radiation shielding material in the form of lead covered by a relatively thin layer of readily deformable material such as steel and the like.

The lead in the combined energy absorbing and radiation shielding means serves a dual function. Firstly, it provides radiation shielding at the ends of the shipping container. Secondly, its energy absorbing capacity is employed to absorb energy under impact. The additional lead supported at the ends of the container increases the weight of the container slightly compared to a container employing only uranium shielding at the opposite ends thereof, but uranium shielding may be employed in the side wall means of the container to achieve substantial weight saving as compared to a container having lead radiation shielding in the side wall means thereof.

The combined energy absorbing and radiation shielding means at the opposite ends of the container serves to absorb energy and to distribute any impact forces applied thereto throughout the body of lead. Since the combined energy absorbing and radiation shielding means associated with the removable closure is supported completely outwardly of the body means and is not directly connected with the sealing surface of the closure means, no deformation occurs in the clamping area of the closure means thereby insuring that an effective seal is maintained between the closure means and the body means. The mounting of the combined energy absorbing and radiation shielding means externally of the main structure of the shipping container provides a number of advantages. The body of lead of the combined energy absorbing and radiation shielding means provides good energy absorbing material especially adapted to absorb impact forces caused by corner drops of the container. Deformation can be tolerated in a separate mass of lead which would otherwise critically distort the shipping container itself if the shipping container were directly impacted with such forces. The body of lead completely fills the relatively thin cover layer of material, and expansion of the lead at higher temperatures which may be caused by a fire or the like is accommodated by stretching the relatively thin cover material. The layer of cover material may be easily formed as a cap for the top and bottom ends of the container and there is no need for this cover material to be punctureproof. Loss of all of the lead as part of the total shielding of the ends of the container is not critical in case of accident since the fixed radiation shielding the container is sufficient to provide adequate safety.

BRIEF DESCRIPTION OF THE DRAWING The drawing illustrates a vertical longitudinal section through a shipping container according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing illustrates a shipping container which may be of any suitable cross-sectional configuration. Referring now to the drawing, the shipping container includes a body means comprising an inner shell 10 having a bottom 12 and an-outer shell 14 having a bottom 16, the body means being formed of a suitable material such as stainless steel or the like. Suitable radiation shielding material 18 is disposed between the inner and outer shells and preferably comprises several uranium castings suitably interconnected with one another. The inner and outer shells 10 and 14 as well as the radiation shielding material 18 therebetween comprise side wall means of the body means of the container.

Further radiation shielding means 20 in the form of a uranium casting is disposed between bottoms 12 and 16 of the inner and outer shells, casting 20 having a suitable joint connection with the radiation shielding means 18 so as to prevent radiation beaming along the interfaces therebetween.

Conventional cooling fins 20 are connected with the outer surface of outer shell 14, the cooling fins in the present case comprising a plurality of vertically extending spaced members.

The upper portion of the body means is provided with an annular clamping shoulder 30, and a pair of annular seals 32 are disposed within suitable grooves provided in this clamping shoulder. A removable closure means or head 40 has a flat bottom surface 42 which is adapted to fit upon should 30 so as to engage the seals 32 thereby providing an effective seal between the interior and exterior of the container when the closure means is in operative position.

The closure means is retained in the operative position illustrated by means of a plurality of threaded cap screws 44 extending through suitable holes provided in an annular flange 46 of the closure means, these cap screws being threaded into correspondingly threaded holes provided in the upper portion of the body means. Radiation shielding means in the form of a uranium casting 48 is supported within the closure means so as to provide suitable radiation shielding at this end of the shipping container.

A first combined energy absorbing and radiation shielding means is indicted generally by reference numeral 50 and includes a body of lead 52 which is covered by a relatively thin layer 56 of a readily deformable material such as stainless steel or the like. This cover material may be on the order of one-eighth inch in thickness so that it can be readily deformed by expansion of the lead under elevated temperature conditions. it will be noted that the combined energy absorbing and radiation shielding means is not directly connected to the sealing surface 42 of the removable closure means. Accordingly, closure means 40 may be formed of a rigid material such as stainless steel whereby an effective seal may be maintained, the combined energy absorbing and radiation shielding means serving to absorb and distribute therewithin forces applied thereto. The body oflead also of course provides additional radiation shielding at the ends of the shipping container.

A second combined energy absorbing and radiation shielding means indicated generally by reference character 60 is provided at the opposite end of the shipping container and includes a body of lead 62 covered by a relatively thin layer of material 64 similar to the material 56 previously described. This combined energy absorbing and radiation shielding means serves the same purpose as that previously described in that it is adapted to absorb energy and distribute impact loads applied to the end of the shipping container as well as to provide additional radiation shielding at the end of the container.

Each of the combined energy absorbing and radiation shielding means of the present invention comprises a body of lead substantially filling the space disposed within a relatively thin cover of readily deformable material. The combined energy absorbing and radiation shielding means are both disposed completely outwardly of the respective ends of the body means of the shipping container and are positioned externally of the main structure of the container in overlying relationship to a major portion of the associated end of the container.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

What is claimed is:

l. A shipping container for radioactive material comprising body means having a cavity therewithin to receive radioactive material, said body means comprising side wall means including radiation shielding material and a plurality of longitudinally extending cooling fins, said body means also comprising end closure means including radiation shielding material at least one of said end closure means arranged to be removably secured to the corresponding end of said body member; and a combined impact absorbing and radiation shielding cap constructed and arranged to be mounted on said removable end closure means non-integrally therewith and outwardly thereof, said cap comprising a substantially solid body of lead encased within a thin cover layer of readily deformable metal. 

1. A shipping container for radioactive material comprising body means having a cavity therewithin to receive radioactive material, said body means comprising side wall means including radiation shielding material and a plurality of longitudinally extending cooling fins, said body means also comprising end closure means including radiation shielding material at least one of said end closure means arranged to be removably secured to the corresponding end of said body member; and a combined impact absorbing and radiation shielding cap constructed and arranged to be mounted on said removable end closure means non-integrally therewith and outwardly thereof, said cap comprising a substantially solid body of lead encased within a thin cover layer of readily deformable metal. 